Hello and welcome to BW!
If she fights every nap and never sleeps more than 45minutes to an hour, there is a chance that she is undertired, rather than overtired. Laura is correct to say that lots of LOs have short naps between 3-6 mos, but they are usually 30-45 mins. 45 and up is generally undertired.
At five months, average A time is 2 hrs - 2hrs 30 mins, and going towards 3 hours as they get towards 6 months. The general structure of sleep is something like 2 1.5-2 hr naps, 1 45 min catnap, and 10-12 hours at night. Sounds like she does great nights!
Here are some excellent tips for wind-down before naps. You don't have to do all of this, feel free to adapt to whatever you and your LO like, as long as you are consistent, she will learn that these things mean it's sleep time. It is a good idea to get her out of the habit of feeding to sleep at this younger age. It can be pretty tough to do when they are older!
What does a good wind down consist of (Includes 4S ritual)And here are some sample EASYs for her age group, they're on the EASY Forum, under 'Activity'.
Sample EASY Routines from 0 - 13mths+HTH.